Read the following paragraphs and mark the letter A, B, C or D to indicate the option that best fits each of the numbered blanks from 1 to 10.

Coral reefs, often referred to as the "rainforests of the sea," are among the most diverse ecosystems on Earth. However, they are facing unprecedented threats due to climate change, ocean acidification, and human activities. The Great Barrier Reef, for instance, has suffered from severe bleaching events, (7) _______.